Question

Shipment	Time to Deliver (Days)
1	7.0
2	12.0
3	4.0
4	2.0
5	6.0
6	4.0
7	2.0
8	4.0
9	4.0
10	5.0
11	11.0
12	9.0
13	7.0
14	2.0
15	2.0
16	4.0
17	9.0
18	5.0
19	9.0
20	3.0
21	6.0
22	2.0
23	6.0
24	5.0
25	6.0
26	4.0
27	5.0
28	3.0
29	4.0
30	6.0
31	9.0
32	2.0
33	5.0
34	6.0
35	7.0
36	2.0
37	6.0
38	9.0
39	5.0
40	10.0
41	5.0
42	6.0
43	10.0
44	3.0
45	12.0
46	9.0
47	6.0
48	4.0
49	3.0
50	7.0
51	2.0
52	7.0
53	3.0
54	2.0
55	7.0
56	3.0
57	5.0
58	7.0
59	4.0
60	6.0
61	4.0
62	4.0
63	7.0
64	8.0
65	4.0
66	7.0
67	9.0
68	6.0
69	7.0
70	11.0
71	9.0
72	4.0
73	8.0
74	10.0
75	6.0
76	7.0
77	4.0
78	5.0
79	8.0
80	8.0
81	5.0
82	9.0
83	7.0
84	6.0
85	14.0
86	9.0
87	3.0
88	4.0

A) Find the average delivery time for the sample of shipments from the data sheet

B) Find the standard deviation of the delivery times for the sample of shipments from the data sheet.

C) Find the size of the sample of shipments from the data sheet.

D) Find the score from the appropriate probability table (standard normal distribution, t distribution, chi-square) to construct a 90% confidence interval .

E) Find the margon of error at 90% confidence level.

If you use Excel, please list what Excel functions would allow me to get this answers for future reference

Answer 1

A) Find the average delivery time for the sample of shipments from the data sheet

Average delivery time = 5.943181818

(by using excel function =average().)

B) Find the standard deviation of the delivery times for the sample of shipments from the data sheet.

Standard deviation = 2.688237275

(Use excel =stdev() function)

C) Find the size of the sample of shipments from the data sheet.

Sample size = n = 88

D) Find the score from the appropriate probability table (standard normal distribution, t distribution, chi-square) to construct a 90% confidence interval .

n = 88

confidence level = 90%

df = n – 1 = 88 – 1 = 87

so, by using t-table or excel, we have

Critical t value = 1.6626

(Use excel =tinv() function)

E) Find the margon of error at 90% confidence level.

Margin of error = t*S/sqrt(n)

Margin of error = 1.6626*2.688237275/sqrt(88)

Margin of error = 1.6626* 0.286567056

Margin of error = 0.4764